Patent document 1 discloses a hydraulic-pressure control device including a pressurization mechanism. This pressurization mechanism includes: (1) a housing; (2) a stepped piston fluid-tightly and slidably fitted in the housing and including a large diameter portion and a small diameter portion; (3) an input chamber provided on a side of the stepped piston nearer to the large diameter portion than to the small diameter portion; (4) an output chamber provided on a side of the stepped piston nearer to the small diameter portion than to the large diameter portion; (5) a high pressure chamber communicating with the output chamber; (6) a high-pressure supply valve provided between the output chamber and the high pressure chamber; and (7) a valve opening member provided on the stepped piston, wherein a master cylinder is coupled to the input chamber, a brake cylinder is coupled to the output chamber, and an accumulator is coupled to the high pressure chamber. When the stepped piston is advanced by hydraulic pressure in the master cylinder, the valve opening member switches the high-pressure supply valve to its open state. Working fluid at high pressure is thereby supplied to the output chamber, so that hydraulic pressure in the output chamber is built up and supplied to the brake cylinder. That is, the hydraulic pressure in the master cylinder is built up and supplied to the brake cylinder, allowing a great braking force to be produced.